Improved extraction of prolamins for gluten detection in processed foods

Authors

• Päivi Kanerva Department of Food and Environmental Sciences, PO Box 66, FI-00014 University of Helsinki, Finland
• Tuula Sontag-Strohm Department of Food and Environmental Sciences, PO Box 66, FI-00014 University of Helsinki, Finland
• Outi Brinck Department of Food and Environmental Sciences, PO Box 66, FI-00014 University of Helsinki, Finland
• Hannu Salovaara Department of Food and Environmental Sciences, PO Box 66, FI-00014 University of Helsinki, Finland

DOI: https://doi.org/10.2137/145960611797471525

Keywords:

barley, celiac disease, gluten, prolamin, rye, wheat

Abstract

A problem in gluten analysis has been inconsistent extractability of prolamins, particularly from processed foods consisting of unknown portions of prolamins from wheat, barley, and rye. This study aimed at improving the extraction of prolamins for immunological analysis, regardless of the cereal species and the production process. The prolamins were extracted with varying concentrations of ethanol, 1-propanol, and 2-propanol. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting were applied to study the protein composition of the extracts and the antibody recognition of the prolamin subgroups. We characterized the affinities of prolamin-specific antibodies that are used in gluten analysis against the prolamin groups that were soluble in 40% 1-propanol. The antibody R5 recognized more abundantly the medium-molecular weight groups, including polymeric proteins, and less the high-molecular weight groups than the anti-ù-gliadin antibody. In the present study, the prolamins were most efficiently extracted by 40% 1-propanol with 1% dithiothreitol at 50 °C . The prolamins were extracted from processed bread samples with efficiency similar to that from untreated meal samples.;